Search Documents

By C. R. Copeland

Airborne dust emission standards are receiving growing attention. This trend is motivated by significant health studies that have shown adverse health effects due to exposure to dust. Currently, the air quality standards are not specific to particles in the nanoparticulate range (<1,000 nm). However, as our understanding of health related matters increases, it is very likely that nanoparticulate standards will be adopted. It was previously believed that typical comminution and material-handling practices could not result in airborne nanoparticulates. However, experimental studies using air monitoring and SEM have verified the presence of nanoparticulates in the air as a result of comminution and material handling. This means that emerging nanoparticulate air quality standards are a real possibility for industrial operations. With this emerging problem facing the minerals industry, effective suppression methods for nanoparticulates should be explored. Systematic studies have indicated that nanoparticulates from silica can be suppressed utilizing hygroscopic reagents such as calcium chloride. This reagent was as much as 93% more effective than water in suppressing silica nanoparticulates.

Jan 1, 2007

By J. Garretson

When mining accidents occur, workers often become trapped and/or incapacitated. Current rescue operations can be dangerous and too slow to produce favorable outcomes. Currently, no method exists for rescue crews to scout ahead at critical times to assess the situation. Sandia National Laboratories (SNL), through a National Institute for Occupational Safety and Health (NIOSH) sponsored program has developed the Gemini-Scout mine rescue platform. The Gemini-Scout was created to assist in underground mine rescue missions. It has been designed to go into potentially hazardous environments to assess the conditions (structural, air quality, temperature). In addition, it will enable two-way communications with potential survivors prior to human rescue teams being able to enter the area. The Gemini platform is a dual tracked-chassis design, which gives the robot excellent mobility in unstructured environments. The design includes a passive 2-degree of freedom joint between two identical bodies allowing for ±30deg of pitch and roll. In addition to the base mobility platform, the Gemini-Scout incorporates many other features to help it succeed in its underground mission. The electronics are mounted in explosion proof housings to ensure safe operations in hazardous gas environments. The platform is also able to operate in up to 18in of standing water with its elevated pan/tilt cameras for navigation. A four-channel video link and Two-way audio on the vehicle help to ensure located survivors can communicate with the robot operators. The platform also incorporates a Mine Safety and Health Administration (MSHA) approved multi-gas sensor to monitor air quality. SNL believes that this technology is broad enough to be appealing to other first responders, such as police, firefighters and medical personnel. Gemini could easily be fitted to handle earthquake and fire scenarios, and it could provide relief in currently inaccessible situations.

Jan 1, 2012

By Kevin Hennings

Screening efficiency models developed to date rely almost exclusively on empirical formulas based upon large amounts of acquired operating data. A screening model was developed using a combination of empirical coefficients and explicit mathematical expressions which quantify screening phenomena. A series of screening tests was run to supply data for purposes of correlation and empirical coefficient evaluation. The model has been implemented as a digital computer program. The validity of the modeling procedure has been established by laboratory testing. Results generated by the model have been used to compile an applications handbook, which can be used to predict screening performance in lieu of using the computer program.

Jan 1, 1982

Development of Cost-Efficient Environmentally Sound Technology for Enhanced Gold Recovery from Rebellious Gold-Containing Raw Materials Study of biochemical leaching performances in gold-bearing sulfide minerals processing enabled to develop environmentally sound technology of enhanced gold recovery from rebellious gold-containing raw materials. It was found that the ?-10 IMO bacteria activity contributes to increasing system oxygen concentrations and incrementing in rates of oxygen delivery onto surface of gold-bearing minerals. Bacteria activity products, ie, amino acids (?), support the formation of such heterocomplexes as [A-Au-CN]- , providing additional gold recovery into solutions. Technological properties of proposed bacteria solutions were studied. It was found that the proposed bacteria inoculants are capable to growing directly in process of raw materials leaching within a large pH range of media containing cyanides and thiosulfates. They oxidise the sulfur to the sulfate, as well as the antimony (III) and arsenic (III) sulfides to the pentads. For the first time, the hydrophobic cell properties, metabolites emulsifying efficiency, adsorption properties, wetting ability, surface tension and electro-kinetic potential of new bacteria strain solutions were studied as compared with chemical solutions. It was found that the proposed bacteria inoculants reduce surface tension at the solvent-mineral and solvent-concentrate phase boundaries. All aforementioned effects enhance mass transfer processes efficiency. IR-spectroscopy of new bacteria strain culture liquid allowed identifying available amino acids which substantially contribute to heterocomplex anion [A-Au-CN]- formation. Active involvement of heterotrophic bacteria in gold dissolving processes was identified. It was shown that the structure of metals complexes is substantially modified at intensive pulp agitation and during long-term storage. Fractional order reaction in biochemical and chemical gold leaching was identified. It evidences that the gold and impurity metals dissolving processes advance in synchronism. The both processes are running in diffusion zone. Biochemical leaching has advantages over chemical leaching, ie&nbsp;it provides enhanced rates of precious metals dissolving, improved gold recovery by 20&nbsp;-&nbsp;30 per cent, decreased cyanide consumption by 50 per cent. At the same time it allows to decontaminate dangerous substances contained in productive solutions produced in rebellious gold-containing raw materials processing. Basic parameters of flotation concentrates leaching by heterotrophic bacteria-assisted processing technology were tried and tested. Technology of gold sorption from leaching solutions was successfully tested.

Sep 13, 2010

By Michael Kaplan

An investigation was conducted of the use of a mechanical rock splitter as the primary means for rock fragmentation in underground hard rock mining systems. Analyses and scale model tests showed that reasonably sized splitters that could be mounted on the booms of conventional drill jumbos were capable of fragmenting over a ton of rock per cycle. Detailed drill-split mining systems were developed for entry development, room and pillar, bench mining, and cut and fill mining. Economic analyses of these systems showed them to be generally competitive with conventional drill-blast methods. Except for bench mining, drill-split offered substantial cost savings over drill-blast. The investigation also included a technical evaluation of the mechanical splitter, an analysis of health and safety, and a determination of the potential applicability of drilling and splitting.

Jan 1, 1979

By D. Allan Coutts

Demonstration projects using hydrogen as a fuel are becoming very common. Often these projects rely on project-specific risk evaluations to support project safety decisions. This is necessary because regulations, codes, and standards (hereafter referred to as standards) are just being developed. This paper will review some of the approaches being used in these evolving standards, and techniques which demonstration projects can implement to bridge the gap between current requirements and stakeholder desires. Many of the evolving standards for hydrogen-fuel use performance-based language, which establishes minimum performance and safety objectives, as compared with prescriptive-based language that prescribes specific design solutions. This is being done for several reasons including: (1) concern that establishing specific design solutions too early will stifle invention, (2) sparse performance data necessary to support selection of design approaches, and (3) a risk-adverse public which is unwilling to accept losses that were incurred in developing previous prescriptive design standards. The evolving standards often contain words such as: ?The manufacturer shall implement the measures and provide the information necessary to minimize the risk of endangering a person?s safety or health.? This typically implies that the manufacturer or project manager must produce and document an acceptable level of risk. If accomplished using comprehensive and systematic process the demonstration project risk assessment can ease the transition to widespread commercialization. An approach to adequately evaluate and document the safety risk will be presented.

May 1, 2007

By Alexander May

The Bureau of Mines conducted studies to determine if phosphogypsum, a waste material from the processing of phosphate rock, contains hazardous toxic materials as defined by the Environmental Protection Agency (EPA) and whether leaching of these toxic materials and radium may occur. Samples of the phosphogypsum stockpiled material were evaluated using the EPA extraction procedure, atomic absorption, neutron activation, x-ray diffraction, and chemical and physical means. Radiological tests performed used both the germanium-lithium and emanation methods. The data show that the phosphogypsum stockpiles are not hazardous toxic waste as defined by EPA criteria. Trace elements and radium are not leached from the phosphogypsum stockpiles. Absorption of trace elements and radium by phosphogypsum is the major reason for their not being leached. The standard error of measurement of radium concentrations was 4.7 pCi/g.

Jan 1, 1983

By R. W. Drier

THE conductivity of copper wire is of prime importance to the electrical industry and consequently to the copper refiner and wire manufacturer. Annealed copper wire has a higher conductivity than hard-drawn wire, but, on the other hand, its tensile strength is lower. In an attempt to explain the reasons for these changes in property or at least to study the conditions existing in these two types of copper wire, the experiments described here were carried on in the Department of Metallurgy of the Michigan College of Mining and Technology. This is only a partial and preliminary report on some of the work done to date on a research program of which the object is an intensive study of copper. It is offered with the hope that, though it is not an exposition of the most rigorous of conclusions, the general trend of inferences which may be drawn will be of value and interest.

Jan 1, 1929

By C. Melvin Lepper

The Bureau of Mines has developed an improved earth resistivity field system which employs a novel technique for obtaining null measurements. The instrument is designed to operate reliably in high-noise environments such as those found in the vicinity of operating mines. The system consists of a low-frequency transmitter, a sensitive receiver and an external battery pack, each in its own case to provide protection from the elements. The receiver and transmitter units have self-contained recharge-able batteries to supply power to the circuitry and separate built-in battery chargers that operate on standard 115 Vac power. The system is portable and simple to operate. Measurement accuracy, reliability, and dynamic range are superior to most commercially available equipment even though less time and effort is required to make null readings. Unlike some commercial systems, long integration times are not required to enhance signal-to-noise ratio in areas of high background noise.

Jan 1, 1974

By Ren G. Dong, Thomas W. McDowell, John Z. Wu, Chris Warren, Dan E. Welcome, Chun L. Dong

Hand forces are important factors for risk assessment of hand-arm vibration syndrome (HAVS).1 Grip force is one of the most important force components in the operation of powered hand tools. A considerable number of studies on grip force have been reported. It is well known that the grip force applied on a cylindrical handle is not uniformly distributed on each axis across the center of the handle cross-section.2 Therefore, maximum and minimum orientations of grip force exist around the handle. Such orientations have not been clearly identified. In a recently proposed international standard (ISO/CD 15230, 2005),3 it is stated that “the direction of the main gripping force is generally parallel to the z-axis defined in ISO 8727.” 4 This assertion is questionable, and further examinations are required. The objective of this study was to establish a fundamental theory on the distribution of the grip force around cylindrical handles. Methods As shown in Fig. 1, the grip force is defined as a vector composed of normal and shear components (FN & FT) in this study. Fig. 2 shows the hand coordinate system defined in this study, together with the ISO systems.1,4 Based on this novel grip force definition, we derived four fundamental properties and a theorem. More significantly, we formulated a novel hypothesis: similar to Mohr’s circle of stress, the normal and shear components can be represented approximately using an ellipse on the plane of the two force coordinates, as shown in Fig. 3. The maximum and minimum grip normal forces are termed as the first principal grip force (F1) and the second principal grip normal force (F2), respectively. Their corresponding orientations are termed as the first principal grip angle (a1) and the second principal grip angle (a2). A series of experiments were conducted to test this hypothesis. Twelve

Jan 6, 2006

By J. S. Stachulak, K. A. Mackinnon

This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and operating conditions are discussed. Common operating problems, such as vibration, parallel operation, mechanical failure, erosion, corrosion, and deficient fan performance are covered. Apart from identifying the potential operating problems, likely causes and suggested remedies are given. Fan type, fan accessories, and likely system effects and fan testing are discussed. Suggestions on what should be covered when evaluating different fan options and proposals and suggestions on the verification of supplier claims and guarantees, including cost of operation, the evaluation of initial capital cost, estimate on maintenance costs, and likely replacement expenditure over the life of the fans. In addition, fan reliability, operational flexibility, suggested construction details and fan vendor past history and experience are reviewed.

Jan 1, 2004

Background Chronology 2008 Positions May 8, 2010 Summit Going Forward Say one thing and do another ??Genuine passion to see our customers succeed?, ?A passion for exceeding our customer?s expectations? Self serving actions to gain competitive advantage at the expense of the customer No single supplier or technology can manage the overall mine and its integrated operation - April 2005: Informal meeting at Toronto CIM 2004 -Unanimous interest - July 2005: Formal Calgary Meeting, developed: - Scope and vision statement , - OEM/OTM communication plan, - industry communication plan - Aug?Nov 2005: Aligned with SMART - Nov 2005?May 2006: Direct OEM, OTM communication - May ?Sept 2006: Developed baseline standards - Sept -April 2007: Developed SMART document - Sept 2007: Document distribution and request OEM OTM response - Jan ?May 2008: Acquired OEM OTM feedback and positions May 2008: Results presented to SMART and discussions on next steps

May 1, 2010

By Sibabrata Patnayak

A major problem during shovel excavation in oil sand mining is the variability of material diggability resulting in varying mechanical energy input, cycle time, energy consumption, wear, and stress loading of shovel dipper-andtooth assembly. This variability greatly influences the mining equipment performance. Different approaches such as empirical ground classification systems, analytical methods, and performance monitoring that are used to determine diggability of groundmass are reviewed. It is concluded that the existing empirical diggability classification systems are site specific and mostly based on rock and therefore, cannot be used for shovel excavation in oil sands. The O&K wedge test is a simple and useful index test for establishing correlations between cutting resistance and geotechnical properties of coal and other soft rock overburden material. But this test, when performed on small size unconfined oil sand samples, may not give reliable indication of diggability because of the boundary conditions on the specimens. Digging predictions made using analytical and laboratory digging models need to be verified with performance monitoring data to better understand the digging effort in oil sands.

Apr 1, 2005

By W. William Culver

James Douglas became known in the nineteenth century for two reasons fundamental to his mining career: (1) his experimental work with copper hydrometallurgy, and (2) his grasp of the idea that the quantity of copper ore matters more than the quality. On the first reason, there is a moment for any technology that’s critically important—when it moves from an area of scientific interest to one that companies are founded on. This paper examines the original 1869 Hunt and Douglas Copper Process in the context of science and engineering as they were in the 1860 and 1870s. It was a “humid” process, developed at Quebec’s Harvey Hill Mine. Chemically, the Hunt and Douglas vat leaching process succeeded, but not the original companies using it. On Douglas’ understanding of ore quality versus quantity, luck had it that the first company to field test the Hunt and Douglas Copper Process was in Chile. The Hunt and Douglas patent made that transition from experimental model to operational plant in 1870 when the Compañia de Minas de la Invernada was organized in Valparaíso. As a joint-stock company, Invernada spread the risk of investing in the revolutionary, but untested, Hunt and Douglas Process. The company brought Douglas to Chile as a consultant in 1871. His experience with hydrometallurgy, combined with what he learned about the copper business while in Chile, set him off on a career in metal mining that both surprised Douglas and made him wealthy.

By Leons Kovisars

Introduction Labor is the major cost element for most mining operations. Labor costs are continually increasing, both in nominal and constant terms. This is true in developed as well as less developed countries. There are two ways to control unit labor costs - labor costs per ton of ore mined. Replace labor with capital (increased mechanization) or improve productivity (reduce the labor force). Every miner is aware of specific inefficiencies at his or her particular operation. But the miner has no comparative measurement standards. So it is difficult to know whether these inefficiencies are major or minor. The miner may also be unaware of large-scale inefficiencies because ongoing labor practices may have caused management complacency. Met Research studied mining labor productivity. The firm collected pilot data by sending direct-mail questionnaires to 320 nonferrous mining operations around the world. The response rate was 27%, of which 78 operations provided full data on production and employment.

Jan 11, 1983

By E. Esponosa-Gomez, J. A. Finch, A. R. Laplante

"Water quality plays an important role in oxide flotation. The effects on selective flotation of fine (1-16 um) pyrochlore of two types of water used at the Niobec concentrator, potable and plant recycle, were assessed. Several pyrochlore collectors and silicate depressants were tested. Water effects were different for each mineral-reagents) combination. In general plant recycle water decreased selectivity and increased reagent consumption. Interpretation of results is given in terms of electrokinetic effects, hydrolysis of cations, and mineral-collector interactions. Two techniques of treatment for plant recycle water, cation precipitation and zeolite adsorption were assessed. The former was found to be more effective under the tested conditions but recycle water continued to give poorer selectivity than the potable.INTRODUCTIONWater quality plays an important role in selective flotation. Specific effects have been reported by many workers (1-6) and in general the better the water quality the more selective is flotation. Water composition depends on origin and the minerals being processed. For example pulp containing salt-type minerals (calcite, apatite, dolomite) will contain more Ca and Mg cations than that from a sulphide deposit. Another source of water contamination is the flotation reagents added to the pulp, particularly if water recycling is practiced."

Jan 1, 1986

By W. Langer

Of the 50 or so most often utilized industrial minerals, more than two thirds are, or have been, produced in the western states of Arizona, Colorado, Idaho, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Utah, and Wyoming. Some commodities, such as natural aggregate, currently are produced in all 13 states; others such as beryllium and iodine are produced in only Utah and Oklahoma, respectively. Together, the 13 western states make a significant contribution to the US industrial minerals industry.

Jan 1, 2007

By Takuji Yamamoto

High-speed TBM excavation requires rapid ground assessment ahead of excavation, particularly in complex grounds. The Tunnel Reflector Tracing technology (TRT) developed by authors, uses seismic reflections to produce volumetric images of ground anomalies. To further minimize interruption in the TBM excavation the authors modified surveying technique switching from cable (wired) to radio (wireless) data acquisition system. This paper presents the outline of the Wireless TRT system, and compares the results for the wired and the wireless surveys. The comparison shows that the wireless system offers high precision data, is more efficient and economical and significantly less intrusive in tunneling operations.

By A. Gene Collins

Potassium, lithium, strontium, barium, and manganese are present in many oilfield brines, None of them except barium is determined routinely in brine analyses. Therefore, sensitive and accurate flame-spectrophotometric methods were developed. Potassium, lithium, and strontium were determined by a standard-addition technique in ethyl alcohol solutions. Barium and manganese were determined in ethyl alcohol and normal propyl solutions, respectively, after interfering substances were removed.

Jan 1, 1962

By A. J. Romeo

The Old Hickory heavy mineral ore body, which lies within the Fall Zone of south central Virginia, has been mined since 1997. There are many differences in this deposit when compared to humate-laden mineral sands mines of southern Georgia and Florida. These differences include an abundance of kaolin-rich clayey sands, highly concentrated and iron-colored heavy mineral sand units, and a base of mineralization that is undulating. For these reasons, the selective approach of dry mining with track excavators is ideal. Grade control in this deposit uses traditional panning techniques and requires an intimate working knowledge of near-by drilling data. Mine geologists train equipment operators to recognize the base of mineralization by such characteristics as a stark color change, significant changes in grain size, and/or considerable, recognizable shifts in the concentration of heavy minerals. The regular pattern of mine site drilling does not always prepare the geologist and digging crews for occurrences of near-vertical contacts between the saprolite basement and the ore sands. These deformed areas, combined with undulating and pinching ore zones, require close monitoring and flexibility by the geologist and the mine operators.

Jan 1, 2005